Generally, a sensing element of the physical quantity sensor detects physical quantity such as angular velocity and acceleration. However, in some cases, an external impact (i.e. an external acceleration) to the physical quantity sensor damages the performance of the sensing element. For example, an angular velocity sensor usually detects angular velocity according to the Coriolis force along a direction of the detection. When the external impact along the direction affects the sensing element, the angular velocity sensor possibly detects a false angular velocity.
In JP-2000-55667-A, an angular velocity sensor is described which dissipates an unwanted vibration which originates from the impact. Specifically, the angular velocity sensor includes a container having a rubber cushion as a vibration-proof body and supports a sensing element with the rubber. Accordingly, the vibration is damped in a propagation path to the sensing element. Thus the unwanted vibration is suppressed.
However, the stiffness of the body decreases below a tolerable limit when the vibration-proof body is too soft (i.e. with low elasticity). On the other hand, if the vibration-proof body is too hard (i.e. with high elasticity) the effect of the damping decreases.